1. Field of the Invention
In general, the present invention relates to an apparatus and system for removing seats. More particularly, the present invention provides an improved puller that utilizes spring loaded J-shaped hooks for removing various seats, valve seats, pump liners and so forth from oilfield fracturing pumps, mud pumps, nitrogen pumps, and other equipment found in the oil and gas industry as well as other equipment utilizing same. It is also understood the current invention may be utilized in any other pump type that utilizes replaceable open face seats.
2. Description of the Prior Art
Due to the nature of seats in general, it is often extremely difficult to remove the seat after it is installed. There are many prior art devices for pulling pump valve seats and liners, but most of them are complex and expensive. If a valve seat puller is complex, it consumes time in the removal of the valve seat which translates into money lost during the down time. It is not unusual for the down time in removing a valve seat with prior art devices to run 8-20 hours.
It is understood that in various piston type reciprocating pumps there are valves which open and close in order to direct the flow. The valve mates to a replaceable seat in order to create a seal, stopping the fluid which is being pumped, moving in the direction it is being forced. Over time with the opening and closing of the valves against seat creates wear causing the valves not to seal. The common term used for worn seats is “washed”. At this time, the seats must be replaced with new ones.
Valve seats in most pumps are generally slightly tapered, with or without an o-ring, for sealing the seat to the pump head. They are typically held in place by the taper, in that they are pressed into place. When a seat is replaced, it is removed with a puller. There are several different types of pullers used which include a two half puller that spreads out to the inside dimension of the seat by threading the puller shaft inside it, opening the two outer halves far enough to catch the bottom of the seat. This is typically done by two people where one lowers the puller shaft down through the seat, while another person reaches the two half parts of the puller through an open port in the head. The person with the threaded shaft then attempts to thread the puller shaft into the expandable halves. A hydraulic jack, such as hollow shaft jack, is then generally utilized to pull the shaft.
Another commonly used puller is a flat plate that hinges on the bottom of the puller body. It is tipped vertically and then inserted through the seat where gravity causes the flat plate to fall horizontally, thus catching the bottom of the seat and pulled with the same hydraulic jack. These types of pullers fail regularly in that they will not withstand very high pulling pressures. The normal practice at this point, when the pullers have failed, is to call a welder to cut the seat out of the pump with an acetylene torch. This naturally exposes the head of the pump to be “nicked” or cut into with the torch that can cause the head to have to be removed and taken to be repaired.
Another example of a prior art valve seat puller is U.S. Pat. No. 3,990,139 issued to Touchet on Nov. 9, 1976. This device utilizes J-shaped hooks wherein the hooks are essentially individual pieces that work in cooperation and are hinged at the top portion to allow the hooks to spread out and engage the valve seat when in position. These J-shaped hooks are not spring loaded and therefore require a mechanical means to spread the hooks out to engage the seat. More specifically and quoting the issued patent, one embodiment of the pipe pulling apparatus 10 comprises a plurality of J-shaped hooks 24 having a J-shaped end or head 26 and a transverse T-shaped other end 25. The hooks 24 are pivotally supported by its T-shaped end 25 in radial slots 33 of support block or plate 22. In another embodiment, the J-shaped hooks are supported in slots 61 in support block 54 by a transverse T-shaped head portion 57, with the opposite end having a J-shaped head 59 for engaging the lower rim of valve seat 52 when pivoting.
This prior art device has several inherent problems due to the configuration of the individual J-shaped hooks and need for the hooks to pivot by a mechanical means. Needless to say any obstruction in the pivot movement would prevent the J-shaped hook from rotating out for extending and thus would not allow for the hook to catch the valve seat. Dirt and debris in the field associated with the use of pumps is more common than not and frequently inhibited the hook from pivoting as needed. Also of note, rust would frequently inhibit the pivot movement requiring cleaning and lubricating of the part to keep it from binding.
Furthermore, sometime the hook would be stuck in the extended position because the pivot problem. This would mean that the J-shaped hook would not pass through the valve seat opening and often would cause further damage when hitting the valve seat. It is not uncommon for the stuck out J-shaped hook to further push down the seat, damage, it and so forth making it even more difficult to remove.
Still furthermore, the prior art device of U.S. Pat. No. 3,990,139 essentially utilizes a threaded shaft to spread the J-shaped hooks as well as to extract the seat once engaged by use of rotational force for lifting. Current valve seats are typically seated in a tighter fashion making the torque required to rotational lift extremely high which leads to failures, stripping of threads, and damage to motors needed to provide the rotational movement.
It is therefore desirable to provide a valve seat puller and or extractor that provides a spring function to spread the j-shaped hooks to engage the seat when desired and eliminate the need for a mechanical system to engage the hooks. It is also desirable to provide a puller that may be utilized with a hydraulic jack to pull the seat up and out without the need for rotational lifting.
Present day drilling operations are extremely expensive, and an effort to increase the overall efficiency of the drilling operation while minimizing expense requires the essentially continuous operation of the drilling rig. Thus, it is imperative that downtime be minimized. The above discussed limitations in the prior art is not exhaustive. Thus, there is a need for an apparatus, method and system to remove valve seats, pump liners, and so forth easily and quickly. The current invention provides an inexpensive, time saving, more reliable apparatus and system where the prior art fails.